My ex signed a form to take me off of our apt lease. He was evicted, and it is now a judgement on MY credit!?

My ex signed the apt form to remove me from our apt lease, and 4 months later he was evicted. I had already moved out, and currently have my own apt (I have paid on time for 8 months now). I was never contacted or served with an eviction notice or court information. I happened to check my credit report, and saw the judgement on my credit. I contacted the apt office/manager to find out why I was added to the judgement, even though I was no longer a tenant. I was told that my info would not be sent to collections for owing this amount but that it will reflect on my credit/records. How do I remove the judgement (which I had no fault in & was never told of any court proceedings) from my records? My score has gone down!!